100+ Head-Fier

Hi - I have a tube question if anyone's up for it. About a year ago I bought from ebay what were advertised as "Match Codes PAIR JAN JHS Sylvania 6AK5W Tube NOS D Getter".

When they turned up, they looked like this:

Very obviously GE branded, although labelled JHS on the boxes.I thought there had been some mix up, but couldn't be bothered to question it with the seller. I thought no more about it, until recently I tried them out again, and they have fast become my favourite tube when using my dt880s. The have the nice accurate soundstage I like with EF95 tubes, but they also have great bass and add just the right amount of warmth to the dt880.

I'd like to buy some more, since I like them so much - but I'm confused - can anyone provide a positive ID? Are they GE or actually Sylvania? Are the two brands the same thing?

Headphoneus Supremus

Joined:
Aug 8, 2010

Posts:
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Hi richdytch,

Crossbranding is very common with vacuum tubes. JHS definitively is Sylvania. Try to look very carefully on the print on the tubes and see if you can find three digit numbers:
188 means GE
312 means Sylvania

(I once bought a lot of 8 Mullard M8100/CV4010. One tube was stamped M8100 over the silk screening of a 5654/6AK5W made in USA Sylvania tube!)

100+ Head-Fier

I just rolled my factory matched pair of Tesla 6f32 into my LD MKIII and my initial impressions are WOW!
Without even being completely being burnt in they are something special.

The most outstanding quality thus far is the Crystal clear sparkling highs, which present themselves with great extension without any hints of sibilance.
with these I find the Highs much more pleasant than the Tung sol 6AJ5 and the the highs of the Tesla's are way more resolved than the Voshkod 6ZH1P-EV.

I find the mids are very neutral they remind me of the Tung Sol 6aj5 mids perhaps a little less warm.
However they are nowhere near the luscious mids of the mullard ef92’s so if you find the mullards to colored you might want to look into a pair of these.

The Bass is deep accurate and clear and very close to the Bass of the Voshkod 6ZH1P-EV perhaps a touch more authoritative...

The soundstage is as wide and deep as any I have heard however it has the added dimensionality of height. I had not been able to discern this before with other tubes but with these tubes there it was.
Highly recommended! I cannot wait to see what they develop into after some burn in.

New Head-Fier

Joined:
Jun 16, 2011

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Hey guys. I've been wanting to tube roll my MKIII for quite a while so today I took the jump and bought a matched pair of "Tung-Sol JTL-6AJ5/6ak5/6J1/EF95" tubes from ebay. I've had a look at my circuit board and it appears to be a Version 4. Are these tubes suitable for that version? I'm not sure where my manual got to. Where I can find out how to set the jumpers for these tubes? (I'm new to this )

Headphoneus Supremus

Hey guys. I've been wanting to tube roll my MKIII for quite a while so today I took the jump and bought a matched pair of "Tung-Sol JTL-6AJ5/6ak5/6J1/EF95" tubes from ebay. I've had a look at my circuit board and it appears to be a Version 4. Are these tubes suitable for that version? I'm not sure where my manual got to. Where I can find out how to set the jumpers for these tubes? (I'm new to this )

Thanks!!!!

Click to expand...

personnally i have a version 2.0(written v 2.0) check where i drew a circle for your model number its probably2.0 then those tubes are fine i have a pair of 6aj5 sound good

Headphoneus Supremus

Hey guys. I've been wanting to tube roll my MKIII for quite a while so today I took the jump and bought a matched pair of "Tung-Sol JTL-6AJ5/6ak5/6J1/EF95" tubes from ebay. I've had a look at my circuit board and it appears to be a Version 4. Are these tubes suitable for that version? I'm not sure where my manual got to. Where I can find out how to set the jumpers for these tubes? (I'm new to this )

Thanks!!!!

Click to expand...

your 6aj5 are part of the ef95 family so put jumper on ef95 5654 side which is the right side of picture . the 2 pins starting from right side put jumper on those 2 pins

100+ Head-Fier

Joined:
Apr 2, 2008

Posts:
102

Likes: 12

No worries, not bad just different. I have a pair of tung sol 6aj5 and a pair of 6ak5 booth good tubes but a different sound signature for each which suprised me.. I have some extra tubes of all makes as I went a little crazy so pm me if there are others you want to try or trade.
Gary